Installation

You can install the add-on directly from your Blender Preferences, pointing to the zip you downloaded.
If you have a previous version installed, it is important to remove it first from the Preferences, restart Blender, and install the new version.

If you are getting errors,  I would recommend following this Clean Install process instead:

- Download the zip file from your Gumroad library or from the Gumroad Photographer page (make sure to be logged in with the account that bought the add-on).

- In Windows Explorer, go to %appdata%\Blender Foundation\Blender\4.1\scripts\addons

- On Linux, go to /home/$user/.blender/4.1/scripts/addons/
or /.config/blender/4.1/scripts/addons/

- On macOS, go to /Users/Username/Library/Application Support/Blender/4.1/scripts/addons 

Note : change the 4.1 in the path above to the number of the Blender version you are using.

- Delete any photographer folder or photographer file that would be in there. You can always copy it somewhere else for backup.

- Unzip the file you downloaded into that same addons folder. You should now have a new photographer folder.

- Start Blender and make sure to activate the add-on in your Preferences (Edit > Preferences > Add-ons)

Troubleshooting

It is possible that you receive an error message like the following one when enabling the add-on: 

PermissionError: [WinError 5] Access is denied: 'C:\\Program Files\\Blender Foundation\\Blender 3.5\\3.5\\scripts\\presets\\photographer' 

This is because the add-on installs preset files and textures during the first activation. If your script folder is located in Program Files, Windows won't allow the add-on to copy these files.

I would recommend installing the add-on in the %appdata%\Blender Foundation\Blender\3.5\scripts\addons or somewhere else that is not write-protected to avoid such problems. In case your Blender is still looking to install scripts and add-ons in the Program Files folder, you may want to change the script path from the Preferences: